If you have ever spotted a USB flash drive cemented into a wall, you may have stumbled across what is known as a Dead Drop. It is part of a global art project borrowing tricks from the world of espionage!

Dead Drops is an international community building "an anonymous, offline, peer-to-peer file-sharing network in public space." In the very early days of espionage, spies needed ways to exchange sensitive material in public without actually meeting. The system was called a "dead drop" and it's different from a "live drop" where the spies actually meet. Typically a dead drop would be something like a loose brick in an alleyway wall.

In 2010, a Berlin-based artist had a fantastic idea. Adam Bartholl decided to adapt the idea for public use. His Dead Drops involve people hiding USB flash drives in different cities all over the world. The drops are embedded into walls, fences, curbs, or anything else they can fit into. The initial idea was that you look up their locations, access the drive, and do what you want with the files. You could add your own, remove or copy the files.

Of course, it’s rather harder to do so without being noticed – plugging a laptop into the wall isn’t exactly inconspicuous. And there’s a small but significant risk involved: accessing random USB sticks on your computer isn’t the smartest thing to do if you value the contents of your hard drive.

When cemented into place, each drive is empty except for a file explaining the group’s manifesto: “A Dead Drop is a naked piece of passively powered Universal Serial Bus technology embedded into the city, the only true public space.”

There are nearly 1500 dead drops with 10 terabytes of combined storage all around the world. The only continent without a dead drop is Antarctica. With all these dead drops, someone is bound to abuse it. In February, a German journalist found something pretty interesting on a dead drop he found in Cologne. On the dead drop was plans for a bomb, along with guides on producing crystal meth and recipes for various deadly poisons.